title: Design, synthesis, and characterization of a single-chain peptide antagonist for the relaxin-3 receptor RXFP3.
abstract: Relaxin-3 is a two-chain disulfide-rich peptide that is the ancestral member of the relaxin peptide family and, together with its G protein-coupled receptor RXFP3, is highly expressed in the brain. Strong evolutionary conservation of relaxin-3 suggests a critical biological function and recent studies have demonstrated modulation of sensory, neuroendocrine, metabolic, and cognitive systems. However, detailed studies of central relaxin-3-RXFP3 signaling have until now been severely hampered by the lack of a readily available high-affinity antagonist for RXFP3. Previous studies have utilized a complex two-chain chimeric relaxin peptide, R3(BΔ23-27)R/I5, in which a truncated relaxin-3 B-chain carrying an additional C-terminal Arg residue was combined with the insulin-like peptide 5 (INSL5) A-chain. In this study we demonstrate that, by replacing the native Cys in this truncated relaxin-3 B-chain with Ser, a single-chain linear peptide of 23 amino acids that retains high-affinity antagonism for RXFP3 can be achieved. In vivo studies demonstrate that this peptide, R3 B1-22R, antagonized relaxin-3/RXFP3 induced increases in feeding in rats after intracerebroventricular injection. Thus, R3 B1-22R represents an excellent tool for biological studies probing relaxin pharmacology and a lead molecule for the development of synthetically tractable, single-chain RXFP3 modulators for clinical use.
authors.affiliation: School of Natural Sciences, Linnaeus University, SE-391 82 Kalmar, Sweden.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Haugaard-Kedström
authors.forename: Fazel
authors.initials: F
authors.lastname: Shabanpoor
authors.forename: Mohammed Akhter
authors.initials: MA
authors.lastname: Hossain
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Clark
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Ryan
authors.forename: David J
authors.initials: DJ
authors.lastname: Craik
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Gundlach
authors.forename: John D
authors.initials: JD
authors.lastname: Wade
authors.forename: Ross A D
authors.initials: RA
authors.lastname: Bathgate
authors.forename: K Johan
authors.initials: KJ
authors.lastname: Rosengren
mesh_terms: D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D008024:Ligands; D008297:Male; D008958:Models, Molecular; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors* / Q000737:chemistry; D012065:Relaxin / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D008024:Ligands; C410092:RXFP3 protein, human; D043562:Receptors, G-Protein-Coupled; D012065:Relaxin